Cool temperatures and a drop in wind speed have offered firefighters relief today, but the New South Wales fire situation remains dynamic and dangerous.

The crisis has claimed at least one life - a 63-year-old man who collapsed and died while defending his home on the Central Coast late yesterday.

Authorities are beginning to get a clearer picture of the scale of destruction and say hundreds of homes have been lost across the state.

In the worst-hit areas in the Blue Mountains, the Rural Fire Service says 30 per cent of properties have been inspected, with 81 confirmed lost and 37 damaged.

More than 20 bushfires continue to burn uncontained in parts of NSW, as more than 2,000 firefighters, including interstate reinforcements, are involved in battling the blazes.

Prime Minister Tony Abbott has praised the efforts of fire crews: "These are ordinary people who, on an extraordinary day, come together to support their community and to protect their fellow Australians."